Thanks gryphon, Daryl & Homer.

gryphon - I will try and contact the number provided.

Homer - Yes looks like PJV is Phil J Vinnicombe. Came across some other guns at Victoria museum signed PJV and confirmed as engraved by Phil J Vinnicombe.
https://collections.museumvictoria.com.au/items/833486
https://collections.museumvictoria.com.au/items/819968